1. Field of the Invention
The invention relates to a voice navigation device and voice navigation method utilized in the voice navigation of vehicles.
2. Related Art
The Satellite Global Positioning System (SGPS) is a system researched and developed by US Defense Department in the 1970s, comprising altogether 28 satellites. The major principle of its application lies in making use of the time required for the radio wave emitted by a satellite to reach a receiver at a ground station in order to calculate the distance between them, meanwhile utilizing the satellite to calculate the longitude, latitude, and the elevation of the receiver at the ground station.
The original purpose of the development of the satellite global positioning system is for military application, however, recently it has been gradually released to the civilian sectors for positioning application. In the past, for defense and security reasons, the US Defense Department has for a long time utilized the establishment of the scrambling codes to purposely reduce the accuracy of the non-military application of the SGPS. As such, the errors of civilian versions of the satellite SGPS system are around 100 meters. Under this circumstance, it is not capable of fulfilling the requirement of monitoring and navigating an ordinary vehicle. Therefore, a certain auxiliary system must be supplemented, so as to increase its positioning accuracy.
In recent years, due to the widespread usage of the civilian and commercial satellite global positioning system, the calls and demands for the US Defense Department to cancel the scrambling and interference of the civilian sector of the SGPS had been ever increasing, and on May 1, 2000 the US government finally agreed and lifted such restrictions on the civilian sector of the SGPS. As such, the error of the SGPS can be reduced to around 10 meters at best, thus significantly increasing the accuracy of the SGPS for civilian application.
The satellite global positioning system for civilian and commercial application can be utilized in: a police car dispatching system, a vehicle navigation system, a passenger transport management system, a taxi dispatching system, a train control and warning system, a cargo transport management system, etc. Nowadays, a vehicle navigation system is very popular in domestic automobile industry, which is used in cooperation/combination with electronic maps, so that the driver in the vehicle is aware of his present position, and is also able to obtain the information about the surrounding environment.
When the Satellite Global Positioning System is used in a vehicle for navigation, the voice navigation device may be utilized to provide convenient direction and reference for the driver through voice broadcasting. However, the problem with the ordinary voice navigation device is that the on-going voice-guidance-item is apt to be interrupted by a new voice-guidance-item, and this will happen even when the on-going voice-guidance-item is of greater importance than the new one. As such, the driving safety may be in jeopardy.